Correlation between the local stress and the grain misorientation in the polycrystalline Al₂O₃ measured by near-field luminescence spectroscopy

Owing to its high spatial resolution, near-field spectroscopy is a useful method for sensing the stress in a narrow region of submicron order. Here, on the basis of the highly resolved images obtained by near-field luminescence spectroscopy, we propose a statistical method of analyzing grain anisotropy-induced stress in polycrystalline Al₂O₃. We focus on two characteristics of a spectra: the intensity ratio and peak shift of luminescence of two lines (R₁ and R₂) from Al₂O₃ to discuss crystal orientation and stress, respectively. By incorporating the concept of the crystal misorientation parameter using intensity ratio, an apparent correlation between the magnitude of stress and the misorientation is found. This correlation analysis provides an important insight for the investigation of local thermal stress in Al₂O₃.